Ioxynil (Ref: ACP 63-303)

Ioxynil (Ref: ACP 63-303)	Last updated: 27/04/2024
(Also known as: M&B 8873; jioxynil; bantrol; ioxynil phenol)

SUMMARY

Data alerts

The following alerts are based on the data in the tables below. An absence of an alert does not imply the substance has no implications for human health, biodiversity or the environment but just that we do not have the data to form a judgement.

Environmental fate	Ecotoxicity	Human health
Environmental fate Moderate alert: Drainflow: Moderately mobile	Ecotoxicity High alert: Birds acute ecotoxicity: High	Human health High alert: Mammals chronic toxicity: High; Endocrine disrupter

GENERAL INFORMATION

Description

A herbicide used for post-emergence control of various weeds. Also pesticide transformation product.

Example pests controlled

Annual broad-leaved weeds

Example applications

Cereals; Onions; Leeks; Garlic; Shallots; Flax; Sugarcane; Forage grasses; Lawns & turf

Efficacy & activity

Availability status

Current

Introduction & key dates

circa 1966, introduced

UK regulatory status

UK COPR regulatory status

Not approved

Date COPR inclusion expires

Expired

UK LERAP status

No UK approval for use

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Not approved

Dossier rapporteur/co-rapporteur

France

Date EC 1107/2009 inclusion expires

Expired

EU Candidate for substitution (CfS)

Not applicable

Listed in EU database

Yes

Approved for use (✓) under EC 1107/2009 in the following EU Member States

ATAustria	BEBelgium	BGBulgaria	CYCyprus	CZCzech Republic	DEGermany	DKDenmark	EEEstonia	ELGreece

ESSpain	FIFinland	FRFrance	HRCroatia	HUHungary	IEIreland	ITItaly	LTLithuania	LULuxembourg

LVLatvia	MTMalta	NLNetherlands	PLPoland	PTPortugal	RORomania	SESweden	SISlovenia	SKSlovakia

Approved for use (✓) under EC 1107/2009 by Mutual Recognition of Authorisation and/or national regulations in the following EEA countries

ISIceland	NONorway

Additional information

Also used in

Australia

Chemical structure

Isomerism

None

Chemical formula

C₇H₃I₂NO

Canonical SMILES

C1=C(C=C(C(=C1I)O)I)C#N

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

NRXQIUSYPAHGNM-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C7H3I2NO/c8-5-1-4(3-10)2-6(9)7(5)11/h1-2,11H

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
iodoxynil	Variant

General status

Pesticide type

Herbicide, Metabolite

Metabolite Type

Soil

Substance groups

Nitrile herbicide

Minimum active substance purity

960 g kg⁻¹

Known relevant impurities

EU dossier - None declared

Substance origin

Synthetic

Mode of action

Selective, systemic with contact action, acts by inhibiting photosynthesis at Photosystem II

CAS RN

1689-83-4

EC number

216-881-1

CIPAC number

US EPA chemical code

353200

PubChem CID

15530

CLP index number

608-007-00-6

Molecular mass

370.91

PIN (Preferred Identification Name)

IUPAC name

4-hydroxy-3,5-diiodophenyl cyanide

CAS name

4-hydroxy-3,5-diiodobenzonitrile

Other status information

Marine Pollutant

Relevant Environmental Water Quality Standards

UK Environment Agency non-statutory standard for the protection of freshwater and saltwater aquatic life: 10 µg l⁻¹ as annual average; 100 µg l⁻¹ as max acceptable conc.

Herbicide Resistance Class (HRAC MoA class)

Herbicide Resistance Class (WSSA MoA class)

Insecticide Resistance Class (IRAC MoA class)

Not applicable

Fungicide Resistance Class (FRAC MOA class)

Not applicable

Examples of recorded resistance

Physical state

White crystalline solid

Related substances & organisms

ioxynil-sodium

ioxynil octanoate

ioxynil-lithium

Can be a metabolite of:

Parent

Formation medium

Estimated maximum occurrence fraction

1107/2009 relevancy

ioxynil-lithium

Soil

Major fraction

ioxynil-sodium

Soil

Major fraction

ioxynil octanoate

Soil

0.526

Major fraction

Formulations

Property

Value

Example manufacturers & suppliers of products using this active now or historically

Bayer CropScience
Nufarm UK
Dow AgroChemicals

Example products using this active

Totril
Hawk
Hocks
Sanoxynil
Certrol
Actril
Trevespan

Formulation and application details

Often supplied as an emulsifiable concentrate or aqueous concentrate

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

Solubility - In water at 20 °C (mg l⁻¹)

3034

High

Solubility - In organic solvents at 20 °C (mg l⁻¹)

73500

Acetone

22200

Methanol

5800

Xylene

37500

n-Heptane

Melting point (°C)

207.8

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

Octanol-water partition coefficient at pH 7, 20 °C

1.58 X 10⁰²

Calculated

Log P

2.2

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

2.72

Dissociation constant pKa) at 25 °C

4.1

Weak acid

Vapour pressure at 20 °C (mPa)

0.00204

Low volatility

Henry's law constant at 25 °C (Pa m³ mol⁻¹)

1.50 X 10^-05

Non-volatile

Volatilisation as max % of applied dose lost

From plant surface

From soil surface

Maximum UV-vis absorption L mol⁻¹ cm⁻¹

237.2nm = 28030, 287nm = 17380

Surface tension (mN m⁻¹)

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

Non-persistent

DT₅₀ (lab at 20 °C)

2.3

Non-persistent

DT₅₀ (field)

Non-persistent

DT₉₀ (lab at 20 °C)

DT₉₀ (field)

DT₅₀ modelling endpoint

Note

EU dossier Lab studies DT₅₀ range 1.8-3 days (normalised)

Dissipation rate RL₅₀ (days) on plant matrix

Value

Note

Dissipation rate RL₅₀ (days) on and in plant matrix

Value

Note

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Moderately fast

Note

Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7

Value

Stable

Note

Stable pH 5 to pH 9 at 22 °C, 10 days

Water-sediment DT₅₀ (days)

4.6

Fast

Water phase only DT₅₀ (days)

3.5

Moderately fast

Air degradation

As this parameter is not normally measured directly, a surrogate measure is used: ‘Photochemical oxidative DT₅₀’. Where data is available, this can be found in the Fate Indices section below.

Decay in stored produce DT₅₀

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d (mL g⁻¹)

K_oc (mL g⁻¹)

Notes and range

Freundlich

K_f (mL g⁻¹)

4.7

Moderately mobile

K_foc (mL g⁻¹)

303

¹/_n

0.92

Notes and range

EU dossier K_f range 1.25-7.60 mL g⁻¹, K_foc range 112-633 mL g⁻¹, ¹/_n range 0.902-0.958, Soils=4

pH sensitivity

Yes - lower the pH the greater the adsorption

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

1.06

Calculated

Low leachability

SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate

Value

3.88 X 10^-03

Calculated

Note

Potential for particle bound transport index

Low

Calculated

Potential for loss via drain flow

Moderately mobile

Calculated

Photochemical oxidative DT₅₀ (hrs) as indicator of long-range air transport risk

8.0

Calculated using the Atkinson method

Below the level of concern for long-range air transport

Bio-concentration factor

BCF (l kg⁻¹)

Whole fish

Low potential

CT₅₀ (days)

Not available

Known soil metabolites

Metabolite

Major/Minor fraction

$Click here for further information on Major/Minor fraction$

Estimated maximum occurrence fraction

Notes

3,5-di-iodo-4-hydroxybenzamide

Major fraction

0.105

3,5-di-iodo-4-hydroxybenzoic acid

Major fraction

0.204

Known groundwater metabolites

None

Other known metabolites

None

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

130

Rat

Moderate

Mammals - Short term dietary NOEL

(mg kg⁻¹)

Rat

High

(ppm diet)

Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)

2.5

Unknown species Reproductive NOAEL

High

Birds - Acute LD₅₀ (mg kg⁻¹)

Colinus virginianus

High

Birds - Short term dietary (LC₅₀/LD₅₀)

1346 mg kg feed⁻¹

Colinus virginianus

Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)

37.6

Colinus virginianus NOEC

Moderate

Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)

> 60

Eisenia foetida

Moderate

Earthworms - Chronic NOEC, reproduction (mg kg⁻¹)

20.0

Eisenia foetida

Moderate

Soil micro-organisms

Nitrogen mineralisation: No significant adverse effect
Carbon mineralisation: No significant adverse effect

Dose: 2.94 mg ioxynil octanoate/kg soil

Collembola

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

Non-target plants

Honeybees (Apis spp.)

Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

> 100

Apis mellifera

Low

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

10.1

Apis mellifera

Moderate

Unknown mode acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Chronic

Bumblebees (Bombus spp.)

Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Mason bees (Osmia spp.)

Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Other bee species (1)

Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)

Mode of exposure

Other bee species (2)

Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)

Mode of exposure

Beneficial insects (Ladybirds)

Beneficial insects (Lacewings) as % Mortality at dose 0.625 kg ha⁻¹

8.4

Chrysoperla carnea

Beneficial insects (Parasitic wasps) as % Mortality at dose 0.625 kg ha⁻¹

55.6

Aphidius rhopalosiphi Adult

Beneficial insects (Predatory mites) as % Mortality at dose 0.625 kg ha⁻¹

98.7

Typhlodromus pyri Protonymph

Beneficial insects (Ground beetles) as % Mortality at dose 0.625 g ha⁻¹

Poecilus cupreus

Aquatic ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Temperate Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

8.5

Oncorhynchus mykiss

Moderate

Temperate Freshwater Fish - Chronic 21 day NOEC (mg l⁻¹)

3.2

Oncorhynchus mykiss

Moderate

Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

Temperate Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)

3.9

Daphnia magna

Moderate

Temperate Freshwater Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)

0.013

Daphnia magna

Moderate

Tropical Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)

Aquatic crustaceans - Acute 96 hour LC₅₀ (mg l⁻¹)

Sediment dwelling organisms - Acute 96 hour LC₅₀ (mg l⁻¹)

2.79

Chironomus riparius

Moderate

Sediment dwelling organisms - Chronic 28 day NOEC, static, water (mg l⁻¹)

0.013

Chironomus riparius

Moderate

Sediment dwelling organisms - Chronic 28 day NOEC, sediment (mg kg⁻¹)

Aquatic plants - Acute 7 day EC₅₀, biomass (mg l⁻¹)

0.027

Lemna gibba

Moderate

Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)

Unknown species

Low

Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)

Mesocosm study data

NOEAEC mg l⁻¹

HUMAN HEALTH AND PROTECTION

General

Property

Value

Source; quality score; and other information

Interpretation

Threshold of Toxicological Concern (Cramer Class)

High (class III)

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

130

Rat

Moderate

Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)

1050

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

0.38

Rat

Other Mammal toxicity endpoints

ADI - Acceptable Daily Intake (mg kg⁻¹ bw day⁻¹)

0.005

Rat SF=100

ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)

0.04

Rat SF=100

AAOEL - Acute Acceptable Operator Exposure Level (mg kg⁻¹ bw day⁻¹)

AOEL - Acceptable Operator Exposure Level - Systemic (mg kg⁻¹ bw day⁻¹)

0.01

Rat 90 day SF=100

Dermal penetration studies (%)

Dangerous Substances Directive 76/464

Exposure Routes

Public

Consumers may be exposed via ingestion of contaminated food

Occupational

May be absorbed through the skin

MRLs

European

EU MRL pesticide database

Great Britain

GB MRL Register

Notes

Drinking Water Standards

Drinking Water MAC (μg l⁻¹)

Mammalian dose elimination route and rate

Moderately metabolised then lost almost completely within 7 days, mainly via the urine

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

Respiratory tract irritant

Skin irritant

Skin sensitiser

No data found

Eye irritant

Phototoxicant

No data found

General human health issues

Possible thyroid toxicant
May cause gastroenteritis, fever and hyperthermia

Handling issues

Property

Value and interpretation

General

IMDG Transport Hazard Class 6.1
Not expected to auto-ignite; Not highly flammable

CLP classification 2013

Health: H301, H312, H319, H331, H361d, H373
Environment: H400, H410

WHO Classification

II (Moderately hazardous)

UN Number

UN2811

Waste disposal & packaging

Packaging Group II (moderate danger)

Shelf-life, storage, stability and reactivity

Chemically stable under standard ambient conditions

TRANSLATIONS

Language

Name

English

ioxynil

French

ioxynil

German

Ioxynil

Danish

ioxynil

Italian

ioxinil

Spanish

ioxinil

Greek

ioxynil

Polish

joksynil

Swedish

ioxinil

Hungarian

ioxinil

Dutch

ioxynil

Norwegian

Record last updated:	27/04/2024
Contact:	aeru@herts.ac.uk
Please cite as:	Lewis, K.A., Tzilivakis, J., Warner, D. and Green, A. (2016) An international database for pesticide risk assessments and management. Human and Ecological Risk Assessment: An International Journal, 22(4), 1050-1064. DOI: 10.1080/10807039.2015.1133242